ASAS-SN Discovery of A Probable Supernova in SDSS J155438.39+163637.6

ATel #6945; S. Kiyota (Variable Star Observers League in Japan), T. W.-S. Holoien, K. Z. Stanek, C. S. Kochanek, A. B. Danilet, G. Simonian, U. Basu, N. Goss, J. F. Beacom (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), Subo Dong (KIAA-PKU), P. R. Wozniak (LANL), J. Brimacombe (Coral Towers Observatory), D. Szczygiel, G. Pojmanski (Warsaw University Observatory), E. Conseil (Association Francaise des Observateurs d'Etoiles Variables), R. A. Koff (Antelope Hills Observatory), B. Nicholls (Mt. Vernon Obs., New Zealand)
on 18 Jan 2015; 03:45 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Thomas Holoien (tholoien@astronomy.ohio-state.edu)

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During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, we discovered a new transient source, most likely a supernova, in the galaxy SDSS J155438.39+163637.6:

 
Object       RA (J2000)     DEC (J2000)      Disc. UT Date   Disc. V mag 
ASASSN-15bd  15:54:38.33   +16:36:38.06      2015-01-17.63    16.6 

ASASSN-15bd was discovered in images obtained on UT 2015-01-17.63 at V~16.6 mag. We also detect the object in images obtained on UT 2015-01-08.64 (V~16.3) and marginally detect the object in images obtained on UT 2015-01-14.63. We do not detect (V>16.8) the object in images taken on UT 2015-01-07.65 and before. An image obtained by S. Kiyota on UT 2015-01-17.85 using a 0.25-m telescope located in Kagayama, Japan, confirms the discovery of the transient. This figure shows the archival SDSS g-band image of the host (left) and the S. Kiyota confirmation image (right). The red circle has a radius of 5" and is centered on the position of the transient in the S. Kiyota image.

The position of ASASSN-15bd is approximately 0.4" North and 1.0" West from the center of the galaxy SDSS J155438.39+163637.6 (z=0.007946, d=34.3 Mpc, via NED), giving an absolute V-band magnitude of approximately -16.2 (m-M=32.68, A_V=0.094). Follow-up observations are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported in part by Mt. Cuba Astronomical Foundation. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.